Senescence surveillance of pre-malignant hepatocytes limits liver cancer development

Upon the aberrant activation of oncogenes, normal cells can enter the cellular senescence program, a state of stable cell-cycle arrest, which represents an important barrier against tumour development in vivo. Senescent cells communicate with their environment by secreting various cytokines and growth factors, and it was reported that this 'secretory phenotype' can have pro- as well as anti-tumorigenic effects. Here we show that oncogene-induced senescence occurs in otherwise normal murine hepatocytes in vivo. Pre-malignant senescent hepatocytes secrete chemo- and cytokines and are subject to immune-mediated clearance (designated as 'senescence surveillance'), which depends on an intact CD4(+) T-cell-mediated adaptive immune response. Impaired immune surveillance of pre-malignant senescent hepatocytes results in the development of murine hepatocellular carcinomas (HCCs), thus showing that senescence surveillance is important for tumour suppression in vivo. In accordance with these observations, ras-specific Th1 lymphocytes could be detected in mice, in which oncogene-induced senescence had been triggered by hepatic expression of Nras(G12V). We also found that CD4(+) T cells require monocytes/macrophages to execute the clearance of senescent hepatocytes. Our study indicates that senescence surveillance represents an important extrinsic component of the senescence anti-tumour barrier, and illustrates how the cellular senescence program is involved in tumour immune surveillance by mounting specific immune responses against antigens expressed in pre-malignant senescent cells.     

From Polymeric Nanoparticles to Dye-containing Photonic Crystals:Synthesis,Self-assembling,Optical Features, Possible Applications

1 Results Self-assembling of monodisperse polymeric nanoparticles is a perspective method of obtaining photonic crystalline materials for optoelectronics,telecommunication industry and optosensorics.For tuning optical characteristics of photonic crystals it is advisable to functionalize nanoparticles by dyes absorbing or emitting light in the vicinity of the photonic band gap,which position depends on the nanoparticle diameter.To prepare monodisperse nanoparticles with the dye-functionalyzed surface emu...     

First record of the genus Setelacher Bouček (Hymenoptera: Eulophidae: Eulophinae) from the Afrotropical region,with description of a new species

ABSTRACT

A new species of the genus Setelacher Bou?ek, S. lasallei sp. nov. Gumovsky and van Noort, is described from the Afrotropical region (Central African Republic, Gabon and Uganda). It confirms the presence of the genus in the region. The only described species of the genus, S. fasciatus Bou?ek, is of Australasian and Indo-Malayan distribution, and one undescribed species was previously recorded from South Africa. All images presented here are available on www.waspweb.org

http://www.zoobank.org/urn:lsid:zoobank.org:pub:D6AA0B15-6EA7-4C93-827C-1807E69BD6D2